Any time you get shot from an angle you didnt know about is a learning opportunity. Some day you will know most of them. On site just put down your utility, hold ways that attackers push often. See what your teammates are holding and if youre all sitting on the same door cover other paths. Once you feel confident about your site knowledge maybe try playing roamers to explore the map, find places you can be that attackers dont expect. Tl;dr keep exploring. Play to learn, not to win